Comment on "Dark Matter Annihilation Can Produce a Detectable Antihelium Flux through $\bar\Lambda_b$ Decays"

Abstract

In a recent Letter, it was suggested that a previously neglected Standard Model process, namely, the production of antihelium-3 nuclei through decays of $\bar\Lambda_b$ baryons can lead to a flux of antihelium-3 from dark matter annihilations detectable by AMS-02. We show that an essential condition for its detectability -- the introduction of the "$\bar\Lambda_b$ tune" of Pythia -- is excluded by a wealth of measurements of (anti-) baryon and (anti-) meson production at accelerators. Moreover, we argue that Monte Carlo generators like Pythia should not be used to predict branching ratios like $BR(\bar\Lambda_b\to \bar u d u (ud_0))$, which control the formation rate of antihelium-3. In particular, we show that $\bar\Lambda_b$ decays which proceed via diquark formation are overestimated by Pythia using its standard settings, which are further enhanced in the "$\bar\Lambda_b$ tune".